package com.sslsocketclient;

public class HexStringUtils
{

    private static final char[] DIGITS_HEX = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};

    protected static char[] encodeHex(byte[] data)
    {
        int l = data.length;
        char[] out = new char[l << 1];
        for (int i = 0, j = 0; i < l; i++)
        {
            out[j++] = DIGITS_HEX[(0xF0 & data[i]) >>> 4];
            out[j++] = DIGITS_HEX[0x0F & data[i]];
        }
        return out;
    }

    protected static byte[] decodeHex(char[] data)
    {
        int len = data.length;
        if ((len & 0x01) != 0)
        {
            throw new RuntimeException("字符个数应该为偶数");
        }
        byte[] out = new byte[len >> 1];
        for (int i = 0, j = 0; j < len; i++)
        {
            int f = toDigit(data[j], j) << 4;
            j++;
            f |= toDigit(data[j], j);
            j++;
            out[i] = (byte) (f & 0xFF);
        }
        return out;
    }

    protected static int toDigit(char ch, int index)
    {
        int digit = Character.digit(ch, 16);
        if (digit == -1)
        {
            throw new RuntimeException("Illegal hexadecimal character " + ch + " at index " + index);
        }
        return digit;
    }

    public static String toHex(String str)
    {
        return new String(encodeHex(str.getBytes()));
    }

    public static String toBinary(String str)
    {
        char[] strChar = str.toCharArray();
        String result = "";
        for (int i = 0; i < strChar.length; i++)
        {
            result += Integer.toBinaryString(strChar[i]) + " ";
        }
        return result;
    }

    public static String fromHex(String hex)
    {
        return new String(decodeHex(hex.toCharArray()));
    }
}